Adaptive Robotics

1. Adaptive Robotics COM2110 Autumn Semester 2008 Lecturer: Amanda Sharkey

2. Recent News: Robot suit for walking in • HAL - short for "hybrid assistive limb" – is a computerized suit with sensors that read brain signals directing limb movement through the skin.The 22 pound (10 kilogram) battery-operated computer system is belted to the waist. It captures the brain signals and relays them to mechanical leg braces strapped to the thighs and knees, which then provide robotic assistance to people as they walk.Cyberdyne, a new company in Tsukuba outside Tokyo, will mass-produce HAL. • Daiwa House Industry Co. will lease HAL suits to Japanese care facilities for the elderly and others for those with disabilities. It plans to rent 500 units over the next year.

3. Last week: • What is a robot? • Introduction to embodied cognition and behaviour-based robotics • Early (classical) robotics: SMPA • Sense model plan action • But mobility and vision – easy for simple organisms, harder for robots • Biological inspiration • Emphasis on body, and environment

4. “the world is its own best model” • This week: • Reactive behaviour • Behaviour-based robotics

5. Norbert Wiener – in 1940’s Cybernetics – Control theory Information science Biology Common principles of control and communication of animals and machines Emphasis on feedback mechanisms 1953 W. Grey Walter Machina Speculatrix Cybernetics

6. Phototropism (photo taxis)

7. Machina speculatrixElsie and Elmer • Two receptors, two nerve cells, two effectors • Receptors: photo-electric cell, and touch sensor • Effectors: drive motor for front wheel, and motor for control of steering. (both full or half speed). • Nerve cells – interlinked amplifiers that controlled motors

8. Grey Walter Soldering Elsie

9. Parsimony – simple reflexes as basis for behaviour • Attraction (positive tropism) – moves towards moderate light • Aversion (negative tropism) moves away from e.g. obstacles and slopes

10. Seeking light: sensor rotated until weak light detected Head towards weak light Back away from bright light Turn and push (to avoid obstacles) Recharge battery – when power low, strong light became attractive. Tortoise returned to recharge – when recharged bright light repelling. Behaviours of electronic tortoise

11. Tortoise behaviours • Dark: steering motor rotated, drive motor half speed. • Wandering round in series of arcs • Moderate light detected:no scanning or steering • Drive towards source of light • Bright light: steering motor half speed, drive motor full speed • Turn away from light

12. Tortoise behaviours cont. • When batteries needed to be recharged – attracted to bright light on hutch • Touch sensor – when shell displaced, would move forward and backwards alternatively • Pushing small obstacles out of the way, going round large ones, and avoiding slopes

13. As Margaret Boden (2006) puts it, “not only did he [Grey Walter] want to save money (the creatures were cobbled together from war-surplus items and bits of old alarm clocks), but he was determined to wield Occam’s razor. That is, he aimed to posit as simple a mechanism as possible to explain apparently complex behaviour” .

14. Avoids the stool and approaches the light

15. Circling two lights (choosing between alternatives)

16. Entering the hutch – the thin light is the pilot light

17. Elsie performing the famous mirror dance

18. Cybernetics – • W.Grey Walter, a cybernetician • Complex behaviour emerges as a result of the interaction between simple behaviours and the environment • Related ideas • animal tropisms, or taxes see Jacques Loeb • Braitenberg vehicles • Reactive behaviour

19. Loeb and animal tropism • |Jacques Loeb 1859-1924 • Fed up with anthropomorphic ramblings of some of the psychologists of his day e.g. Ramones (the Darwinian) • Developed his theory of forced movement or tropism – he used the term “taxis” • Published The Mechanistic Conception of Life in 1912

20. Loeb • Objected to previous anecdotal approach of Georges Ramones. • Ramones emphasised similarities between cognitive processes in humans and animals • Objections to Ramones’ methods led to Lloyd Morgan’s canon • “In no case is an animal activity to be interpreted in terms of higher psychological processes, if it can be fairly interpreted in terms of processes which stand lower in the scale of psychological evolution and development”

21. “Electric Dog” 1912

22. “Electric dog” 1912 • Designed by Hammond and Miessner, built by Miessner • Phototropic machine, with negative feedback device of rear steering wheel that oriented it towards light • First biorobotic machine • Loeb called it the “artificial heliotrope machine”

23. Electric dog continued • Loeb called the machine the “artificial heliotrope machine” • Like moths (natural heliotrope machines) – which are attracted to light by “the same mechanical process as that by which the axis of the stem of a plant puts itself in the direction of the rays of light” (Loeb, 1905) • Loeb saw the artificial heliotrope machine (or electric dog) as confirmation of his theories. • Moth-like behaviour produced by simple attraction to light.

24. See also “Phillidog” exhibited in 1929: • The “dog”, who was sensitive to light, would follow an electric torch and turn or circle round as often as desired. When, however, the light was brought too near and put just in front of his nose he became annoyed and started to bark” [de Latil, 1957] • These machines guided by light – Grey Walter’s tortoises autonomous, and actively sought light

25. Squee: An electric squirreldesigned and constructed in 1951 by Edmund C. Berkeley. It would hunt for “nuts” (tennis balls) when a light was shone on them.

26. Animal behaviour • Reflex: rapid automatic involuntary response triggered by environmental stimuli e.g. escape behaviour • Loeb - Taxes: behavioural responses that orient the animal towards or away from a stimulus. E.g. trail following in ants • Fixed action patterns: time-extended response patterns, triggered by stimulus.e.g. song of crickets

27. The taxes of the coastal snail • Negative photo taxis (photophobia) when in normal upright orientation • Photo taxis when upside down • Negative Geotaxis – needs to move away from gravitational pull of the earth. • This combination of taxes allows it to reach food.

28. Combining Taxes

29. So far … Grey Walter (1953) Electric Dog (1912) Loeb and animal taxis Simple behaviour plus interactions with the world Little (or no) internal representation See also Braitenberg’s vehicles “gedanken experiments”

30. Braitenberg vehicles • Valentino Braitenberg (1984) • “Vehicles: experiments in synthetic psychology” • Vehicles with simple internal structure that generate behaviours that appear complex. • Like Grey Walter’s tortoise – systems fixed, and not reprogrammable • Vehicles used inhibitory and excitatory influences, directly coupling sensors to motors

31. Braitenberg (1989) • “get used to a way of thinking in which the hardware of the realisation of an idea is much less important than the idea itself”

32. Vehicle 1

33. Vehicle 1 • His innovation with this vehicle: the propulsion of the motor is directly proportional to the signal being detected by the sensor; so, the stronger the sensed signal, the faster the motor.

34. E.g. moving in water, with temperature sensor. • Will slow down in cold and speed up in warm • Appears to dislike warm water • Underlying idea – the observer of the system may infer a more complex mechanism than the one that actually underlies the system.

35. Vehicle 2: Fear and aggression

36. Vehicle 2a and 2b • 2a: if sources directly ahead, vehicle will charge at it. Otherwise will turn away from it (“coward”) • 2b: if source to the side, will charge at it (“aggressive”).

37. Vehicle 3: Love

39. Vehicle 4

40. Vehicles appear more complex than they are – • Easy to overestimate complexity, and assume they have knowledge, are deciding what to do, etc.

41. Reactive behaviour • Stimulus-response • Fixed response to inputs from environment • Can give the illusion of intelligence • Are insects purely reactive? • Limitations for robotics – e.g. dead ends

42. Rodney Brooks • Rodney Brooks developed the subsumption architecture in the 1980s • This revolutionised reactive robotics. He called this behaviour-based robots

43. Subsumption architecture Brooks (1986) A Robust Layered Control System for a Mobile Robot. IEEE Journal of Robotics and Automation RA-2, 14-23

44. Key aspects of subsumption architecture • Distributed layered control • Behavioural decomposition • Increasing levels of competence • Incremental construction • Conflict resolution through subsumption mechanism • Little sensor fusion and no central models

48. Subsumption Architecture cont. • Robot controller is embedded into collection of pre-programmed parallel condition-action rules, or reflexes. • The behaviour of the system is the result of interacting simple behaviours (emergence). • Robot provided with a range of behaviours, and environment determines which is in control at any one time. • Design principle: keep it simple

50. Brooks (1991) ‘Intelligence without representation’ • GOFAI approach: studying individual competences, e.g. vision, or planning • Instead – study complete creatures that behave • Understand simple intelligences first • Ability to move about in, and sense environment (evolved first, took longer) • vs • planning, problem solving, language etc. (evolved later in less time)